It will be very helpful to your learning experience if you have access to a Perl installation that allows downloading and installation of CPAN modules. It will be worth some effort to achieve this.

However, for the purposes of running CountZero's example code, the two most important modules ('pragmas' in Perlish) to use in place of Modern::Perl and at the beginning of all code are use warnings; use strict;
(IMHO). If your Perl installation does not offer these fundamental modules, it should be considered seriously b0rken.

In addition to using the above-mentioned modules (pragmata), you will also need to either replace the say() function with some variation of the print built-in, e.g. print $string, 'string', ..., "\n";
or else enable the feature via the feature pragma: use feature 'say';
in Perl versions 5.10+.